In the aftermath of the knowledge economy, smart corporations begin to realize that the proverbial "if we only know what we know" also includes "if we only knew what our customers know." In this paper, the authors discuss the concept of Customer Knowledge Management (CKM), which refers to the management of knowledge from customers, i.e. knowledge resident in customers, in contrast to knowledge about customers, e.g. customer characteristics and preferences prevalent in previous work on knowledge management and customer relationship management. Subsequently, five styles of CKM are proposed and practically illustrated by way of corporate examples.